Helicopter rotor blades, and in particular tail rotor blades are prone to failure due to abrasion caused by particulate matter present in the air. Many methods have been tried so as to prolong the life of the tail rotor assemblies. These methods include adhesively bonding stainless steel strips to the leading sections of the tail rotor blade. The abrasion strip is used as a sacrificial layer which is to be replaced as it wears away with usage. These rotor blades are subject to quite extensive stresses and it is important that the bonding between the abrasion strip and the rotor blade be effective to withstand the stresses developed. A problem with such prior art abrasion strips is that the adhesive bonding of the stainless is quite difficult to obtain and is quite commonly the source of premature failure due to the adhesive failure between the abrasion strip and the rotor blade. The debonding of the abrasion strip from the rotor blade can result in catastrophic failure of the rotor blade assembly and/or gear box due to an imbalance condition of the rotor blade.
Prior art strips are adhered to the rotor blades by an adhesive system which typically depends upon an oxide film generated by acid etching. However, oxide films are typically very unstable, are typically unevenly formed, can cause corrosion and/or unfavorable surface finishes. Such techniques for bonding stainless steel to typical aluminum blades have been shown to be insufficient for the rigors of flight and the severe environment to which the rotor blades are subjected.
The present invention provides an improved rotor blade having an abrasion strip which provides improved bonding between the abrasion strip and rotor blade. The abrasion strip is in turn bonded to the rotor blade.